For instance, a blow fan unit is a well-known unit that generates the air that prevents the ambient temperature of each computer from rising to an excessive value in the room that a plurality of computers are located. As one example of the blower fan units, there is a blow fan unit for blowing the air while rotating so as to blow the air for cooling in various directions. For instance, refer to Japanese Laid-opened Patent Publication No. 2001-295796, Japanese Laid-opened Patent Publication No. 2001-355593 and Japanese Laid-opened Patent Publication No. 2005-104186. As this blower fan unit blows the air to a plurality of locations in the room, the room is evenly cooled.
Here, each computer located in a room has a different state of operation from one another. Therefore, each computer has a different level of heat generation, namely a different level of temperature rise occurs at a plurality of locations in the room. When such a room is cooled, it is difficult to evenly cool the room by simply rotating the blower fan unit. On the other hand, even if the room is evenly cooled, there is a demand to avoid, for instance, a complicated rotation mechanism because of the cost of the blower fan unit.